Flammability reduction systems, such as on-board inert gas generation systems (OBIGGS), nitrogen generation systems (NGS), flammability reduction systems (FRS), and fuel tank inerting systems (FTIS), are commonly used to reduce fuel tank combustion. In these systems, pressurized air from an engine, e.g., engine bleed air or process air, is passed through a membrane module, such as an air separation module (ASM), to separate oxygen from the process air, producing an oxygen-depleted inert gas such as primarily nitrogen-enriched air (NEA). The inert gas is introduced into the ullage (i.e., the space above the liquid fuel) in the fuel tank where it displaces the flammable fuel/air mixture to reduce the risk of an explosion or fire.
This process air, however, typically contains undesirable material, including particulate contaminants, as well as water and oil aerosols. This undesirable material can degrade the performance of the ASM.
However, while some filters for filtering process air are available, there is a need for improved filters.